/*
 * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#ifndef _NETINET_IN_ARP_H_
#define	_NETINET_IN_ARP_H_
#include <sys/kernel_types.h>

struct sockaddr_dl;
struct sockaddr_in;

/*!
	@function inet_arp_lookup
	@discussion This function will check the routing table for a cached
		arp entry or trigger an arp query to resolve the ip address to a
		link-layer address.
		
		Arp entries are stored in the routing table. This function will
		lookup the ip destination in the routing table. If the
		destination requires forwarding to a gateway, the route of the
		gateway will be looked up. The route entry is inspected to
		determine if the link layer destination address is known. If
		unknown, the arp generation function for IP attached to the
		interface is called to create an arp request packet.
	@param interface The interface the packet is being sent on.
	@param ip_dest The ip destination of the packet.
	@param ll_dest On output, the link-layer destination.
	@param ll_dest_len The length of the buffer for ll_dest.
	@param hint Any routing hint passed down from the protocol.
	@param packet The packet being transmitted.
	@result May return an error such as EHOSTDOWN or ENETUNREACH. If
		this function returns EJUSTRETURN, the packet has been queued
		and will be sent when an arp response is received. If any other
		value is returned, the caller is responsible for disposing of
		the packet.
 */
errno_t inet_arp_lookup(ifnet_t interface, const struct sockaddr_in *ip_dest,
			struct sockaddr_dl *ll_dest, size_t ll_dest_len, route_t hint,
			mbuf_t packet);

/*!
	@function inet_arp_handle_input
	@discussion This function should be called by code that handles
		inbound arp packets. The caller should parse the ARP packet to
		pull out the operation and the relevant addresses. If a response
		is required, the proto_media_send_arp function will be called.
		
		This function will lookup the sender in the routing table and
		add an arp entry if necessary. Any queued packets waiting for
		the arp resolution will also be transmitted.
	@param interface The interface the packet was received on.
	@param arp_op The arp operation, ARPOP_REQUEST or ARPOP_REPLY
	@param sender_hw The sender hardware address from the arp payload.
	@param sender_ip The sender IP address from the arp payload.
	@param target_ip The target IP address from the arp payload.
	@result 0 on success or an errno error value on failure.
 */
errno_t inet_arp_handle_input(ifnet_t ifp, u_int16_t arpop,
			const struct sockaddr_dl *sender_hw,
			const struct sockaddr_in *sender_ip,
			const struct sockaddr_in *target_ip);

/*!
	@function inet_arp_init_ifaddr
	@discussion This function should be called in two places, when an IP
		address is added and when the hardware address changes. This
		function will setup the ifaddr_t for use with the IP ARP
		functions. This function will also trigger the transmission of a
		gratuitous ARP packet.
		
		When the SIOCSIFADDR ioctl is handled, the data parameter will
		be an ifaddr_t. If this is an IP address, inet_arp_init_ifaddr
		should be called. This is usually performed in the protocol
		attachment's ioctl handler.
		
		When the event handler for the protocol attachment receives a
		KEV_DL_LINK_ADDRESS_CHANGED event, the event handler should call
		inet_arp_init_ifaddr for each interface ip address.
		
		For an example, see bsd/net/ether_inet_pr_module.c in xnu.
		Search for inet_arp_init_ifaddr.
	@param interface The interface the packet was received on.
	@param ipaddr The ip interface address.
 */
void	inet_arp_init_ifaddr(ifnet_t interface, ifaddr_t ipaddr);

#endif _NETINET_IN_ARP_H_
